But the higher the ozone level in a particular city, the more likely its residents were to die of lung disease.

然而，在一个特定的城市里，臭氧水平越高，居民死于肺病的可能性就越大。

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WMO scientists assess and monitor air pollutants such as ground-level ozone,smog, particulate matter, sulfur dioxide and carbon monoxide.

VOA: standard.2009.03.23

Her previous research had shown that, when the sun grows brighter, the ozone level rises too: it is up to 2% higher at solar maximum.

ECONOMIST: The earth��s climate: Solar rash and earthly fever | The

Scientists think they have identified one key reason why ground-level ozone remains stubbornly high in Europe.

BBC: London's clue to stubborn ozone levels

At ground level ozone is a dangerous pollutant, but at altitude it blocks the passage of harmful ultraviolet light.

ECONOMIST: Atmospheric science: Fake flakes | The